Computer-implemented method for detecting a corneal vertex

A computer-implemented method for detecting a position of a corneal vertex, the method comprising:

• recording a frontal image of a head and a lateral image of the head,
• calibrating the frontal image and the lateral image to one another, and
• determining a position of a corneal vertex in space from the frontal image and the lateral image with a geometric position determination, the geometric position determination including:
• selecting the frontal image and the lateral image to not overlap or selecting only mutually non-overlapping regions of the frontal image and the lateral image to detect the position of the corneal vertex.

A computer-implemented method for detecting a position of a corneal vertex, the method comprising:

• recording a frontal image of a head and a lateral image of the head,
• calibrating the frontal image and the lateral image to one another,
• determining a position of a corneal vertex in space from the frontal image and the lateral image with a geometric position determination, the geometric position determination including:
• determining a position of the corneal vertex in space to a first approximation as the point of intersection q of:
• a first view ray, tangential to the cornea, from a lateral camera recording the lateral image, with
• a second view ray, directed onto the pupil, from a frontal camera recording the frontal image, and
• calculating the position of the corneal vertex according to a=q+μ*v+μ*w, wherein a denotes the position vector of the corneal vertex in space after carrying out the correction calculation, q denotes the position of the corneal vertex to a first approximation, μ denotes an empirical value or an actual value for the distance between a pupil center and the corneal vertex, v denotes a unit vector in the spatial direction from the pupil center to the frontal camera and w denotes a unit vector in the viewing direction extending through the center of a corneal sphere.

A computer-implemented method for detecting a position of a corneal vertex, the method comprising:

• recording a frontal image of a head and a lateral image of the head,
• calibrating the frontal image and the lateral image to one another,
• determining a position of a corneal vertex in space from the frontal image and the lateral image with a geometric position determination, the geometric position determination including:
• performing a correction calculation of the position of the corneal vertex,
• detecting a position of a reflection point of a flash,
• producing the flash when recording the frontal image and the lateral image and the position of the corneal vertex in space is determined to the first approximation as a position of the reflection point of the flash on the cornea, and performing at least one of:
• calculating the position of the corneal vertex in the horizontal direction proceeding from the reflection point by adding Δx=+/−r*sin (½*(arccos z/a+arctan x/(z−v))) to the x-coordinate, wherein r denotes an empirical value or an actual value for the corneal radius, a denotes the distance between the optical center of the frontal camera recording the frontal image and the reflection point, x and z denote the x- and z-coordinates of the reflection point in a coordinate system with the origin at the optical center of the frontal camera, wherein the viewing direction of the frontal camera corresponds to the z-direction and the x-direction is horizontally orthogonal to the z-direction and, when observed in the z-direction, points to the right, and v denotes the distance between the light source producing the flash and the optical center of the frontal camera in the z-direction;
• or
• calculating the position of the corneal vertex in the y-direction proceeding from the reflection point by adding Δy=+/−r*sin ½*(arctan l/(d−v)), wherein r denotes an empirical value or an actual value for the corneal radius, d denotes the distance between the optical center of the frontal camera and the reflection point in the z-direction, v denotes the distance between the light source producing the flash and the optical center of the frontal camera in the z-direction and l denotes the distance between the light source and the optical center of the frontal camera in the y-direction, wherein the y-direction is orthogonal to the x-direction and to the z-direction and points upward in space.